Two types of quantum-confinement characters for the bound states in the InGaN/GaN quantum wells

The (Ga1−xInxN)Nw(GaN)Nb(Ga1−xInxN)Nw(GaN)Nb single and multiple quantum wells (SQWs and MQWs) are investigated theoretically using the sp3s⁎sp3s⁎ tight-binding (TB) method with inclusion of spin–orbit interaction. This study explores the effects of barrier thickness Lb, well width Lw, indium content x   and valence-band offset (VBO) on the quantum confinement (QC) characteristics of the bound states in the well and on the electronic transitions. The calculations are based on the validity of two assumptions: the virtual crystal approximation (VCA) for the structure of the alloyed Ga1−xInxNGa1−xInxN wells, and the macroscopic theory of elasticity (MTE) for the structure of the computational supercell as a whole. The results demonstrate the following main trends: (1) the existence of two types of QC characteristics for the bound states in the GaInN alloyed wells. The nitrogen p-level (EpN=2.71eV, which is associated with InN TB parametrization), displays a threshold/edge that divides the bound states into two types: (i) block-like localized states (in the energy range EpN

► The sp3s⁎ tight-binding method is used to study Ga1-xInxN/GaN super-lattices and quantum wells.
► The results show the existence of two types of confinement characters inside the wells.
► Singlet-like states exist at the bottom and block-like (wave packet) states at the top of the well.
► A limitation of the indium content in the well and its dependence on the well thickness is also shown.
► The excellent agreement between our results and the available PL data corroborates our claims.